WASILLA, Alaska (CNN) - Sarah Palin is putting her opposition to stem cell research on the back burner for the sake of the Republican ticket.

John McCain's campaign released a radio ad Friday that calls he and Palin "mavericks" who will, if elected, back stem cell research "to help free families from the fear and devastation of illness."

"Medical breakthroughs to help you get better, faster," says the radio ad, which according to the campaign is running in key battleground states. "Change is coming. McCain, Palin and congressional allies. The leadership and experience to really change Washington and improve your health."

McCain and his campaign have said the senator supports research that uses stem cells, including the embyronic variety. But Palin does not.

Questioned about the issue in a debate during the 2006 race for Alaska governor, Palin invoked her "pro-life position" and referred to "that centeredness that I have of respecting life and the potential of every human life."

She added that she could not support research that "would ultimately end in destruction of life."